Search Results (8)

This study investigated the feasibility and effectiveness of a commercial top-down stereolithography (SLA)-based system for the additive manufacturing of zirconia dental prostheses. Yttria-stabilized zirconia–resin slurries were prepared, and zirconia objects were fabricated using a top-down SLA system. Thermogravimetric–differential thermal analysis was used to examine the resin, while X-ray fluorescence spectroscopy and X-ray diffraction were used to analyze the printed samples. The microstructures of additively manufactured and subtractively manufactured zirconia were compared using field emission scanning electron microscopy (FE-SEM) before and after sintering. Biaxial flexural strength tests were also conducted to evaluate mechanical properties. The green bodies obtained via additive manufacturing exhibited uniform layering with strong interlayer adhesion. After sintering, the structures were dense with minimal porosity. However, compared to subtractively manufactured zirconia, the additively manufactured specimens showed slightly higher porosity and lower biaxial flexural strength. The results demonstrate the potential of SLA-based additive manufacturing for dental zirconia applications while also highlighting its current mechanical limitations. The study also showed that using a blade to evenly spread viscous slurry layers in a top-down SLA system can effectively reduce oxygen inhibition at the surface and relieve internal stresses during the layer-by-layer printing process, offering a promising direction for clinical adaptation. Full article

Acid-etched zirconia has emerged as a high-strength alternative to traditional glass ceramics for laminate veneers in aesthetic dentistry. This randomized, double-blind controlled clinical trial aimed to evaluate the one-year clinical performance of zirconia veneers etched with a hydrofluoric-nitric acid mixture and bonded using a 10-methacryloyloxydecyl dihydrogen phosphate (MDP) containing polymeric adhesive system, compared to lithium disilicate veneers. Fifty-two patients were treated with either translucent zirconia or lithium disilicate veneers, and restorations were bonded using light-cured resin-based adhesives. Clinical parameters, including veneer survival, esthetics, marginal adaptation, postoperative sensitivity, and periodontal health, were assessed using modified United States Public Health Service (USPHS) criteria and periodontal indexes at 2 weeks, 6 months, and 12 months. Both materials showed high survival rates with no statistically significant differences in clinical outcomes. One zirconia veneer debonded early but was successfully rebonded without fracture, while one lithium disilicate veneer fractured upon debonding. The findings support the viability of acid-etched zirconia veneers bonded with polymer-based adhesives as a durable and esthetic restorative option. The study highlights the clinical relevance of polymeric bonding systems in enhancing zirconia veneer performance and reinforces their role in modern adhesive dentistry. Full article

This study evaluated the internal and marginal accuracy (trueness and precision) of zirconia laminate veneers fabricated using the DLP printing and milling method, employing 3D analysis software program. The maxillary central incisor tooth of a typodont model was prepared by a dentist and scanned using a desktop scanner. An anatomical zirconia laminate was designed using computer-aided design (CAD) software and saved in a standard tessellation language (STL) format. Thirty zirconia laminates were manufactured using a milling machine (MLL group) and a DLP printer (PTL group). All the specimens were scanned, and their internal and marginal areas were edited accordingly. The root-mean-square value was used to assess the accuracy of the internal and marginal areas of the zirconia laminates. Statistical significance was evaluated using the Mann–Whitney U test. Statistically significant differences were found in RMS values for both groups in the internal and marginal areas (p < 0.001 and p = 0.034, respectively). The MLL and PTL groups differed significantly in terms of precision (p = 0.017), but not at the margin (p = 0.361). DLP-printed zirconia laminates demonstrated stable and consistent performance, making the technique a reliable option for producing esthetic prostheses. Full article

DLP printing is a new method for producing zirconia laminates that ensure clinically acceptable gaps in the internal, marginal, and incisal regions. A typical model of a central maxillary incisor was prepped by a dentist and scanned. The laminate was designed using CAD software version 2023. The laminates were fabricated using a milling machine (LSM group) and a DLP printer (LAM group) (N = 20). The gap was evaluated using the silicone replica method at designated measurement points. Statistical analyses were performed. The Shapiro–Wilk and Kolmogorov–Smirnov tests indicated a non-normal distribution, and the Mann–Whitney test was used. The LSM group had wider gaps than the LAM group except at point E (59.5 µm). The LAM group had wider gaps than the LSM group, except at points H (51.70 µm). No significant differences were observed between the LSM and LAM groups at any of the labiolingual measurement points. In the mesiodistal plane, a significant difference was observed between the two groups at point G, which was adjacent to the mesial side (p < 0.05). The results of this study indicate that DLP printing offers an innovative approach for producing zirconia laminates, as the incisal, internal, and marginal gaps are within clinically acceptable ranges compared with the AM method. Full article

This in vitro study aimed to evaluate the final shade of translucent zirconia laminate veneers with varying thicknesses over teeth with different shades. Seventy-five chairside computer-aided design/computer-aided manufacturing (CAD/CAM) shade A1 third-generation zirconia dental veneers, with thicknesses of 0.50 mm, 0.75 mm, and 1.00 mm, were placed on resin composite teeth with shades ranging from A1 to A4. The laminate veneers were divided into groups based on thickness and background shade. All restorations were evaluated with a color imaging spectrophotometer, to map the veneer surface from A1 to D4. Regardless of the thickness or background shade, all dental veneers showed color alteration from the original shade. Veneers with 0.5 mm thickness tended to display the B1 shade, while veneers with 0.75 mm and 1.0 mm thickness primarily exhibited the B2 shade. The thickness of the laminate veneer and background shade significantly modified the original shade of the zirconia veneer. One-way analysis of variance was performed and a Kruskal–Wallis test was used to determine the significance between the three veneer thicknesses groups. The results indicated that the thinner restorations showed higher values with the color imaging spectrophotometer, suggesting that thinner veneers may result in more consistent color matching. This study underscores the importance of carefully considering thickness and background shade when selecting zirconia laminate veneers, to ensure optimal color matching and overall aesthetic outcomes. Full article

The aim of this study was to compare bond strength resin composites to porcelain laminate veneers in the indirect repair method to composite resins used in the direct repair method for cases of porcelain veneer fracture of zirconia-based fixed dental prostheses. In the study, the groups were formed with different percentages of areas to be repaired to mimic porcelain fractures in the mouth. The experimental group of veneered zirconia were as follows: Group A = 100% Zr surface; Group B = 70% Zr, 30% porcelain surface; Group C = 50% Zr, 50% porcelain surface; Group D = 30% Zr, 70% porcelain surface; Group E = 100% porcelain surface. The repairs of the specimens were made using composite resin systems in half of the groups and using porcelain laminate veneers in the other half. Specimens were embedded in acrylic blocks before surface treatments and repairs were applied. After surface conditioning, laminate veneers were applied to the first half of the groups, and composite repair systems were applied to the second half of the groups. After all specimens were aged by thermal cycling, their bond strength values were measured using a Universal Testing Machine, and the obtained data were recorded. The specimens were examined with a stereomicroscope and classified according to failure types (adhesive/cohesive/mixed). Bond strength values were evaluated based on independent-samples t-test statistics. According to the comparisons among the groups, the bond strength of the indirect repairs made with the laminate material was higher than the bond strength of the repairs made with the composite. There was a statistically significant difference in favor of the indirect repair groups among all groups except for Group C. The highest bond strength was found in Group A in the indirect repair method, while the lowest bond was found in the direct repair method in Group E. Adhesive failure was mostly seen in the groups that were repaired with the composite. Full article

Zirconia electrodes with dendritic patterns were fabricated by stereolithographic additive manufacturing (STL-AM). A solid electrolyte of yttria-stabilized zirconia (YSZ) was selected for oxygen separation in the molten salt electrolysis of aluminum smelting without carbon dioxide excretion. Thereafter, 4, 6, 8 and 12-coordinated dendritic structures composed of cylindrical lattices were designed as computer graphics. The specific surface area of each structure was maximized by changing the aspect ratio. The spatial profile and surface pressure of the hot liquid propagation in the dendrite patterns were systematically visualized by computational fluid dynamics (CFD). During the fabrication process, a photosensitive resin containing zirconia particles was spread on a substrate, and an ultraviolet (UV) laser beam was scanned to create a two-dimensional (2D) cross-section. Through layer laminations, three-dimensional (3D) objects with dendritic structures were successfully fabricated. The ceramics were obtained through dewaxing and sintering. Full article

Combining stainless steel with zirconia components by powder technological shaping routes for manufacturing of multifunctional parts is an advantageous and promising one-step method making expensive and time-consuming additional joining steps redundant. However, several requirements for co-shaping and co-sintering of the very different compound partners have to be met. The microstructural and chemical constitution of the interface between both materials plays an important role for the mechanical properties, durability and corrosion resistance of the manufactured parts. In the present study, different shaping techniques for co-shaping of stainless steel and zirconia are introduced. The microstructure and the interphase properties of metal/ceramic hybrid parts have been investigated for samples made by tape casting, subsequent lamination and co-sintering. Nevertheless, the results of this study are valid for components made by other hybrid shaping processes as well. The interfaces were characterized by TEM, FESEM, EDX, and X-ray diffraction. Furthermore, the hydrothermal stability of the material compound was investigated. Full article